In recent years, there have been developed various kinds of organic electronic elements such as an organic electroluminescence element, an organic photoelectric conversion element, an organic photoreceptor for electrophotography, and an organic transistor.
An organic electronic element is an element which performs an electric job using an organic substance. This element is expected to exhibit the merits, such as energy saving, low cost, and flexibility, and this element is directed attention as a technique which will replace the conventional inorganic semiconductor using silicon.
These organic electronic elements are elements which emit light, control an electric current and voltage, generate electricity or keep the charge by irradiating with a light, by leading an electric current through a very thin membrane made of an organic substance through an electrode.
The electroluminescence element (hereafter it is called as an EL element), which is one of the electronic elements, consumes only a small amount of electric power. There has been increased a need for a surface light element with a volume small, and it is paid attention as one of such surface light elements. And these EL elements are divided roughly into an inorganic EL element and an organic EL element by the material to be used.
An inorganic EL element generally gives a high electric field at a light emitting portion, and an electron is accelerated in this high electric field to collide with a luminescence center, thereby a luminescence center is exited, from which light is emitted. On the other hand, an organic EL element injects an electron and a hole into a light emitting layer from an electron injection electrode and a hole injection electrode, respectively. The, both of the injected electron and hole are combined in the light emitting layer to making an organic material into an excited state.
When this organic material returns from an excited state to a ground state, light is emitted. Compared with an inorganic EL element, there is an advantage that an organic EL element can be driven with a low voltage. Taking advantage of the merit that an organic EL element emits light on a plane, the development as a thin and flexible illumination application is expected.
In particular, in the field of the organic EL element for illumination, efficiently manufacturing a high efficient element is expected.
As a way of increasing the efficiency of an organic EL element, the method of using a phosphorescence emitting compound is known. It is possible that a phosphorescence emitting compound emits light with higher efficiency than conventional fluorescence emitting compound.
It is especially important that a phosphorescence luminescence emitting compound is used in a laminated structure. Still higher efficiency can be obtained by laminating various functional layers such as a positive hole transport layer, a light emitting layer, and an electron transport layer.
Moreover, an organic photoelectric conversion element is an electronic element having a similar structure as the above-mentioned organic electroluminescence element. It is an element having a structure in which a light emitting layer in an organic E1 element is changed with an electricity generating layer composed of a thin layer of an organic compound, and the electricity generating layer is sandwiched between electrodes. Electric power is generated when a light is irradiated thereon. Therefore, when the organic photoelectric conversion element of a thin film is used as a solar cell, a miniaturization and a weight saving will be easy, and also it will become a solar cell which can obtain a stabilized output even under the low illumination ambient or the elevated-temperature ambient compared with the solar cells of the existing inorganic semiconductor system.
Also in an organic photoelectric conversion element, like an organic EL element, a carrier trap will be formed in an electricity generating layer by the effect of water and oxygen, and concentration of the carrier which is generated by charge separation will be prevented. As a result, this will lead to not only decline in generation efficiency, but it will decrease the lifetime of an element. Therefore, in the organic photoelectric conversion element, similarly as in an organic EL element, it has been investigated the ways to secure the performance of the element by using the sealing material which has barrier property to gas constituents, such as water and oxygen, as is described in Patent document 4.
On the other hand, a wet process is paid attention as a production method which enables to produce a variety of constituting organic layers of the aforesaid organic EL element and organic photoelectron converting element with high manufacturing efficiency. In the conventional vacuum deposition method, large-sized vacuum devices are needed, and at the same time, it was required time for the operation to achieve vacuum of a substrate and the vacuum evaporation process, and the utilization efficiency of material was also low.
About formation of the functional layers by a wet process, there was proposed a coating method of a solution in which materials having a low solubility or a polymer is dissolved in a fluorine-containing solvent (for example, refer to Patent documents 1 and 2).
However, for example, when a high efficient organic EL element is intended to form using a phosphorescence luminescence compound by a wet process, during the process of laminating a functional layer, there is a problem that the underlaying layer may be dissolved at the time of the upper layer application.
As a way of dealing with such a problem, there is known a method of applying an upper layer using a solvent which does not easily dissolve the underlaying layer. For example, since a light emitting layer is hardly dissolved into a polar solvent, there was proposed a method of applying the electron transport layer which is located an upper layer with a polar solvent (for example, refer to Patent document 3).
However, when an organic EL element of a large area suitable for an illumination application is intended to produce, and the organic layer (electron transportation layer) is applied on the light emission layer using a polar solvent such as alcohol, it was found that an emission unevenness may be produced.
Moreover, compared with the case in which the same electron transport layer is vapor-deposited, it was also found that efficiency was deteriorated greatly.    Patent document 1: JP-A No. 2002-216956    Patent document 2: JP-A No. 2004-265672    Patent document 3: JP-A No. 2007-116008    Patent document 4: JP-A No. 2004-165512